As such oil supply devices, a device is conventionally proposed which includes: a mechanical pump that is operated by power from an engine to generate an oil pressure; a linear solenoid valve that regulates the oil pressure from the mechanical pump to output the regulated oil pressure from an output port to an output port oil passage; an electromagnetic pump that generates an oil pressure by an electromagnetic force to output the generated oil pressure from a discharge port to a discharge port oil passage; and a spool relay valve that has a spool having a plurality of lands and a sleeve (housing) accommodating the spool such that the spool can move in the axial direction, and that is operated by a signal pressure generated based on the oil pressure from the mechanical pump (see, e.g., Patent Document 1). In this device, a first land, a second land, and a third land as the plurality of lands are formed side by side in the axial direction in this order in the spool. In the sleeve, an input port (mechanical pump-side input port) connected to the output port oil passage, an output port connected to a clutch oil passage, an input port (electromagnetic pump-side input port) connected to the discharge port oil passage, and a drain port connected to a drain oil passage having a check valve attached thereto are formed in this order in the axial direction. The sleeve has a first oil chamber defined by the opposing surfaces of the first land and the second land, and a second oil chamber defined by the opposing surfaces of the second land and the third land. When the signal pressure is equal to or higher than a predetermined pressure, the relay valve allows the mechanical pump-side input port to communicate with the output port via the first oil chamber, allows the electromagnetic pump-side input port to communicate with the drain port via the second oil chamber, and shuts off communication between the electromagnetic pump-side input port and the output port by the second land being located between these ports. When the signal pressure is lower than the predetermined pressure, the relay valve allows the electromagnetic pump-side input port to communicate with the output port via the first oil chamber, shuts off communication between the mechanical pump-side input port and the output port by closing the mechanical pump-side input port by the first land, and shuts off communication between the electromagnetic pump-side input port and the drain port by the second land being located between these ports. With this configuration, even if oil having a high oil pressure leaks from the first oil chamber to the second oil chamber with the mechanical pump-side input port communicating with the output port via the first oil chamber and with the electromagnetic pump-side input port communicating with the drain port via the second oil chamber, this oil can be drained from the second oil chamber via the drain port, the drain oil passage, and the check valve. A proper oil pressure can thus be maintained in the discharge port oil passage.
[Patent Document 1] Japanese Patent Application Publication No. 2012-122560 (JP 2012-122560 A)